That's great, it starts with an earthquake, birds and snakes, an aeroplane..." -- R.E.M., "It's the End of the World as We Know It (and I Feel Fine)"

Look, out in the Internet: It's a meme! It's a movie! It's "Snakes on a Plane," the B-movie that just might transcend its low-budget roots to become the most influential film of the year. Not because of its plot (about, er, snakes on a plane) or its star (the uber-cool Samuel Jackson), but because of the impact it's having in the off-screen, online world.

"Snakes on a Plane" (SoaP for short) won't be released until August. But it's already generated an Internet buzz heard around the world -- a buzz so loud it might signal a seismic shift in the relationship between merchandisers and consumers. SoaP is currently exhibit A in the chaotic debate over viral marketing, an advertising approach that, when it works, publicizes a product contagiously through word of mouth. One might even say that SoaP has started a revolution -- quick, tell a friend!

Not since 1999's "Blair Witch Project" has a film spawned so much free, grassroots enthusiasm among a youthful demographic studios usually spend millions courting. What's more, "Snakes on a Plane" achieved its cult status while still in production, thanks to a title absurd enough to spawn fan sites, homemade T-shirts, and a host of faux movie posters and trailers on communities like YouTube.com. When its studio, New Line Cinema, contemplated changing the film's name to the generic "Pacific Air Flight 121," it discovered that "Snakes on a Plane" had grown popular enough to enter online parlance as another way of saying "s -- happens." New Line wisely decided to leave the title alone, and went on to embrace SoaP's fan base by adding five extra days of shooting to amp up the film's over-the-top elements and, per fan requests, letting Jackson deliver a line about "m -- snakes on the m -- plane."

Will others try to replicate this formula? Count on it -- but don't count on their succeeding. Viral marketing relies on creating memes -- cultural ideas that replicate and spread like viruses -- and online memes are inherently anarchic and prone to mutation.

For example, a publicist would have had to be clairvoyant -- and more than a little twisted -- to have predicted the explosion of "Brokeback Mountain" parodies swamping the Internet with the release of the film's misleadingly sappy trailer. And like the "Brokeback" parodies, the "Snakes on a Plane" frenzy is purely a consumer-generated phenomenon. William Gibson, whose 2003 book "Pattern Recognition" explored the world of viral marketing, thinks the spontaneity of an Internet meme makes it hard to manufacture. "The power of 'Snakes on a Plane' is that it emerged from someone having the strength to let go," he says. "The producers of the thing let go of the creative reins when they saw that the blogosphere had taken it over and was telling the story differently. That upped the ante, and it started feeding on itself. You can't create that in-house. You have to be willing to put it out there and let it capture people's imagination."

If marketers want to catch an Internet audience, they'll have to move quickly. Memes travel at hyper speed. On YouTube, MySpace and trend-spotting blogs, anyone with rudimentary photo-manipulation skills can churn out a film parody in an afternoon. A day later, that parody can replicate worldwide, only to be forgotten in 48 hours, when the next meme du jour catches the public interest.

As attention spans decrease and grassroots creativity grows, the power balance between buyer and seller has started to shift: Online customers aren't content to consume a product -- they chew it up and spit it out as something new.

Entertainment corporations are now thinking twice about sending cease-and-desist orders to fans who celebrate and publicize products through appropriation (also known as copyright infringement).

Increasingly, TV producers monitor their programs' online communities and even give onscreen shout-outs to ardent fans, whether its playing up a lesbian subtext in "Xena, Warrior Princess" and "Law and Order: SVU" or launching an Internet alternative-reality game a la "Lost."

And with reality shows like "American Idol" and "Big Brother," consumers are the ones determining outcomes." The era of 'cease-and-desist' is over," says Henry Jenkins, director of the Comparative Media Studies Program at the Massachusetts Institute of Technology. "Producers are courting fans and catering to their expectations. They're ready to serve that buzz. There's a back-and-forth discussion taking place, and 'Snakes on a Plane' is a fantastic example of this dialogic relationship." Jenkins' latest book, due in August (about the same time SoaP hits theaters) is called "Convergence Culture: When Old and New Media Collide." He also heads MIT's Convergence Culture Consortium, which consults with media companies on how to engage online fan communities. "Media are rewiring their relationship to their consumers," he says. "They should stop worrying about losing control; they lost control a long time ago," he says. "They have to be more approachable and less prohibitory."

They also have to learn that what works as a print or TV ad won't always fly online.

"The instincts that you need to make a commercial movie -- a popcorn movie that appeals to the largest number of people -- are the opposite of the instincts you need to make a viral movie," says Seth Godin, author of "Unleashing the Idea Virus." But, he adds, "the paradox isn't permanent. You can hire a blogger to start these things for you. It's not as good as the real thing, but that doesn't matter. These marketers are selfish liars. They're willing to ruin something in order to sell it."

Nonetheless, some Internet aficionados such as Gibson remain optimistic in the face of corporate perfidy. "I'm not worried about people cracking the code and using it to sell adult diapers or CDs," he says. "Memes are a collaborative thing. I think it would be difficult to fake or synthesize one of those. The viral stuff that works seems to be natural. Besides, there's more prestige in detecting and killing a synthetic meme than in spreading it."

The SoaP meme began, as most great things do these days, with an individual blog entry. Screenwriter Josh Friedman recounted his adventures with doctoring a script for a movie about -- why not? -- snakes. Snakes on a plane. Snakes on a plane with Samuel Jackson. Could it get better? It could not, reasoned SoaP fanatic Brian Finklestein, a law student at Georgetown University who started SnakesonaBlog.com last year as part of his quest to be invited to the movie's world premiere. His blog has since morphed into SoaP central, gathering news, rumors and the latest spasms of SoaP-inspired creativity.

While appreciating his efforts, New Line has kept its corporate hands to itself. "They're excited about what's going on online, but they realize if they get involved directly, the organic, spontaneous feel will be gone," Finklestein says. "A lot of what's fun about this is that people are doing everything on their own. If the studio became involved, it would lose whatever charm and cache it has. I've gotten phone calls from marketers asking what they can do to make this work for them. The answer is that there's not much you can do -- except not sue your audience. The music industry can learn from this."

Maybe it will. "We're in a transition period where everyone agrees that media is becoming more participatory, but the conditions of the participation are under debate," Jenkins says. "Right now, the culture is being shaped by top-down decisions made in corporate boardrooms and bottom-up decisions made in teens' bedrooms. It's the intersection of those two forces that will determine the future of media."

And what of "Snakes on a Plane," the latest and greatest example of participatory media, the movie that launched a thousand memes? "All I hope," Gibson says, "is that it's as delightfully, sublimely bad as we dream it'll be."